This invention relates to a floating caliper disc brake including a stationary brake support and a floating caliper slidable coaxially with respect to the axis of the brake disc in two straight-line guides, wherein the straight-line guides are a guide groove in the one component and a projecting part on the other component and wherein measures are taken to permit an elastic displacement of the floating caliper transversely with respect to the guide direction by action of the brake torque.
A floating caliper disc brake of this type is described in U.S. Pat. No. 3,625,314. The straight-line guides of the brake support are very critical parts of floating caliper disc brakes. For braking it is necessary for the floating caliper to be slidable as easily as possible and rattling in its straight-line guides must be avoided. During braking, the floating caliper must not tilt. This occurs easily since the braking torque urges the brake caliper with a high force into one of its two straight-line guides, while the brake-actuating piston tries to displace the floating caliper still further. Taking into consideration further that floating caliper disc brakes, owing to their necessary arrangement in the wheel dish of automotive vehicles, are exposed to contaminants and corrosive media, such as salt water, to a great extent, it will become evident that it is very difficult to meet all these requirements without raising the price of the floating caliper disc brake disproportionately.
U.S. Pat. No. 3,625,314 referred to above discloses a floating caliper brake wherein the brake caliper extends with projecting parts into grooves of the brake support. Resilient angle sheet iron parts are inserted into these grooves. The brake shoes of the known floating caliper disc brake are attached to the floating caliper, and bear additionally against the brake support. Consequently, when braking, the brake caliper initially floats in the direction of the brake torque until it abuts against a firm stop in one of its straight-line guides. The clearance in the other straight-line guide is not increased by this displacement of the brake caliper, since the brake support includes resilient parts and the brake shoes are arranged to bear against it such that the straight-line guide of the brake support--being opposite to the actuation direction of the brake torque--is displaced in the direction of the brake torque and thus follows the displacement of the brake caliper.
The design of this prior known floating caliper disc brake is very complicated and as a consequence expensive to manufacture. A floating caliper disc brake design will be substantially simpler if the brake shoes exclusively bear against the brake caliper. Such a design is shown in e.g. U.S. Pat. No. 3,616,879. The straight-line guides of this design are concave molds in the brake support, into which the brake caliper extends with one guide projecting part. The guide projecting parts are each embraced by a guide steel sheet, which is axially fixed in the concave molds. The brake caliper is thus displaced on actuation of the brake with its guide projecting parts relative to the guide steel sheets.
In this prior known floating caliper brake there is the danger that the guide projecting parts cannot be shifted any more on the guide steel sheets if corroded or dirty which is the case in automotive vehicles that have not been in use for a long time.
As a result, the brake can initially be actuated to a reduced degree only, and with increasing wear it cannot be actuated at all.